Have you seen this plant? Giant hogweed is spreading across the country, and can be dangerous to human health if not handled properly.

Keep invasive species out of your garden

Now that it’s gardening time, do your part to keep invasive species out of your yard

With spring planting season nearly upon us, the Thompson Nicola Invasive Plant Management Committee (TNIPMC) is reminding the public to be careful when selecting plants and animals for their ponds and gardens.

“Many invasive plants start looking attractive this time of year,” says Mike Dedels, TNRD Invasive Plant Management Coordinator. “Adding them to your gardens or ponds may seem like a good idea, until they take hold and start to spread.”

Some species listed on the provincial noxious weed list, such as flowering rush, can sometimes be found in retail garden centres. Flowering rush is regarded as one of the top five worst invasive alien plants in Canada due to its major ecological impact on natural ecosystems. Others, such as orange hawkweed, are found on roadsides and make their way into gardens.

Following the Invasive Species Council of BC’s popular “PlantWise” and “Don’t Let It Loose” programs, the TNIPMC urges the public to garden using only non-invasive species, in order to prevent the spread of unwanted and invasive plants and animals into the environment. The public can access resources and information by visiting www.beplantwise.ca.

The B.C. government has proclaimed May 2019 as Invasive Species Action Month to raise public awareness of invasive species, which are plants or animals that are not native to the province or are found outside of their natural distribution areas. These organisms can disrupt habitat, displace native species, and negatively impact the environment and economy.

Among the invasive species of which people should be aware in this region are spotted knapweed, leafy spurge, hoary alyssum, burdock, and common tansy. Another troublesome—and dangerous—plant is the giant hogweed. The Nature Conservancy of Canada (NCC) is urging people across the country to document sightings of the towering green plant, as giant hogweed is one of Canada’s most dangerous plants, and poses a real human health concern.

The plant is visible now, and flowering, so it is easy to identify. The plant’s clear, toxic sap can cause rashes, blistering, third-degree burns, and temporary—or even permanent—blindness if it touches the body and is then exposed to the sun.

Infestations have been spreading in Canada, with discoveries in the Atlantic provinces, Quebec, and across Ontario. In B.C., giant hogweed has been found in the Lower Mainland, Fraser Valley, Gulf Islands, and central to southern Vancouver Island. The plant was brought to Canada from Eastern Europe and Asia in the 1940s as a decorative, horticultural plant.

NCC national conservation biologist Dan Kraus says one issue is that people think it would be an interesting garden addition, and move it from garden to garden or collect the seeds and plant them. “A single plant can produce thousands of seeds and it can spread quickly,” he says. “The seeds are dispersed when they fall into rivers and streams, and can be dispersed short distances by the wind. Because it’s a tall perennial, giant hogweed can take over large areas along rivers and streams, shade out all of our native vegetation, and nothing can grow under it sometimes. In Europe, dense stands of giant hogweed along rivers have caused erosion, and it has been identified as a serious threat to salmon spawning habits in Great Britain.”

Kraus urges people to not take a specimen of the plant or touch it. Anyone who finds giant hogweed should have it removed professionally by people wearing protective gear. People may also contact their local municipality, along with provincial invasive plant and species councils, who take records of sighting.

Kraus also encourages people to report it by using the https://inaturalist.ca app. By downloading the app on your phone, it allows you to take a picture of a species and share it with plant experts who can help identify it. The app will automatically map it as well, so people can see where giant hogweed is spreading.

Invasive species can be spread as a result of people going about their spring and summer outdoor recreation. Activities such as camping, hiking, biking, fishing, boating, horseback riding, and driving ATVs can unintentionally spread invasive species into our rivers, streams, and forests.

“Many invasive species have few natural predators to control them,” says Kraus. “Once they get into ecosystems, they’re often able to spread and out-compete our native plants and animals for space, water, food, and other resources.

“People may unknowingly be contributing to the spread of invasive species when they are enjoying the outdoors through their recreational activities. That’s why it’s important to share information and these steps so that people can minimize the spread of these invasive species to new areas in Canada.”

The NCC also notes that domestic cats can have a significant impact on populations of migratory birds, reptiles, and small mammals, and are considered one of the world’s 100 most invasive species. Cats that are brought to cottages and camps can kill birds and other wildlife of conservation concern, and should be kept indoors, or on a leash outside.

The TNRD’s bio-control program helps private landowners control invasive plants for free. For more than 20 years, the TNRD has been collecting and releasing bio-control insects for knapweed, hound’s-tongue, and dalmatian toadflax.

The bio-control insects are “host specific” and will not attack native vegetation or even other weedy species.

Bio-control is a long-term commitment, and results may take three to 10 years depending on the species and site variables. If you would like more information about the bio-control program, contact the TNRD at (250) 377-6297 or go to www.tnrd.ca.


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Spotted knapweed is one of the most invasive species within the TNRD area.

It looks pretty, but leafy spurge is considered an invasive species in the TNRD area.

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